Two distinct strains of the coronavirus (SARS-CoV-2) are currently spreading in the world population, one of which is much more virulent than the other, show the work of Chinese scientists.
The new coronavirus is responsible for a new infectious respiratory disease called COVID-19 (for CoronaVIrus Disease ). The first cases were reported in Wuhan City in December 2019.
Recent analyzes by teams from Peking University and the Shanghai Pasteur Institute indicate that the virus has mutated at least once to date. Genetic analysis of 103 SARS-Cov2 genomes shows the existence of two strains (designated L and S ).
The S is the oldest and least aggressive strain. It is responsible for around 30% of infections.
The L appeared later and is more aggressive. It would also spread faster. Its presence would however tend to decrease, perhaps due to human intervention which would have exerted, according to the researchers, a more severe selective pressure on this strain.
This work, published in the National Science Review (New Window ), is based on very preliminary data. Researcher Jian Lu and his colleagues say that more exhaustive studies will allow in the coming months to better understand the evolution and epidemiology of SARS-Cov2 and COVID-19.
Remember that a virus usually tends to lose its virulence by mutating and spreading from person to person. However, this is not always the case.